Knock sensor systems and methods for valve recession conditions

ABSTRACT

In one embodiment, a method is provided. The method includes receiving a signal representative of an engine vibration transmitted via a knock sensor, wherein the knock sensor is disposed in an engine. The method additionally includes deriving a valve wear measurement during operation of the engine based on the signal. The method further includes communicating the valve wear measure.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/877,363, entitled “KNOCK SENSOR SYSTEMS AND METHODS FOR VALVERECESSION CONDITIONS” and filed on Jan. 22, 2018, which are herebyincorporated by reference in its entirety.

BACKGROUND

The subject matter disclosed herein relates to systems and methods forvalve recession conditions, and more specifically, to knock sensorsystems and method applied to valve recession conditions.

Combustion engines will typically combust a carbonaceous fuel, such asnatural gas, gasoline, diesel, and the like, and use the correspondingexpansion of high temperature and pressure gases to apply a force tocertain components of the engine, e.g., piston disposed in a cylinder,to move the components over a distance. Each cylinder may include one ormove valves that open and close correlative with combustion of thecarbonaceous fuel. For example, an intake valve may direct an oxidizersuch as air into the cylinder, which is then mixed with fuel andcombusted. Combustion fluids, e.g., hot gases, may then be directed toexit the cylinder via an exhaust valve. Accordingly, the carbonaceousfuel is transformed into mechanical motion, useful in driving a load.For example, the load may be a generator that produces electric power.As the valves (e.g., valve seats) wear, valve clearance may be reducedand valve recession may occur. It would be beneficial to improvedetection of valve recession and wear.

BRIEF DESCRIPTION

Certain embodiments commensurate in scope with the originally claimedinvention are summarized below. These embodiments are not intended tolimit the scope of the claimed invention, but rather these embodimentsare intended only to provide a brief summary of possible forms of theinvention. Indeed, the invention may encompass a variety of forms thatmay be similar to or different from the embodiments set forth below.

In a first embodiment, a method is provided. The method includesreceiving a signal representative of an engine vibration transmitted viaa knock sensor, wherein the knock sensor is disposed in an engine. Themethod additionally includes deriving a valve wear measurement duringoperation of the engine based on the signal. The method further includescommunicating the valve wear measure.

In a second embodiment, a system includes an engine control systemcomprising a processor configured to receive a signal representative ofan engine vibration transmitted via a knock sensor, wherein the knocksensor is disposed in an engine. The processor is further configured toderive a valve wear measurement during operation of the engine based onthe signal. The processor is additionally configured to communicate thevalve wear measurement.

In a third embodiment, a tangible, non-transitory computer readablemedium storing code is provided. The code is configured to cause aprocessor to receive a signal representative of an engine vibrationtransmitted via a knock sensor, wherein the knock sensor is disposed inan engine. The code is additionally configured to derive a valve wearmeasurement during operation of the engine based on the signal, and tocommunicate the valve wear measurement.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a block diagram of an embodiment of an engine driven powergeneration system in accordance with aspects of the present disclosure;

FIG. 2 is a side cross-sectional view of an embodiment of a pistonassembly in accordance with aspects of the present disclosure;

FIG. 3 is an embodiment of an engine noise plot of data measured by theknock sensor shown in FIG. 2 in accordance with aspects of the presentdisclosure;

FIG. 4 is an embodiment of a combustion signature and a valve signatureplotted over a first complete intake, compression, combustion andexhaust cycle in accordance with aspects of the present disclosure;

FIG. 5 is a flow chart of an embodiment of a process suitable foranalyzing a vibration data and applying a lookup table;

FIG. 6 is a graph illustrating an embodiment of various valve closingangles graphed at various operating engine hours; and

FIG. 7 is a graph showing an embodiment of various crank degrees (e.g.,valve closing degrees) for convertion into valve lift measurements.

DETAILED DESCRIPTION

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

The techniques described herein include the use of one or more knocksensor systems and methods that may detect a dynamic response of avarious gas engine components during engine operations to deriveconditions related to the components and component conditions, includingvalve recession. For example, knock sensors signals related to a varietyof engine components may be detected, including cylinder head components(e.g., cylinder head and gaskets), cylinder block components (e.g.,cylinder block, cylinder sleeves), valves train components (e.g.,valves, valve seats, valve stems), camshaft and drive components (e.g.,camshaft, cam lobes, timing belts/chains, tensioners), piston components(e.g., pistons, piston rings, connection rods), crankshaft assemblycomponents (e.g., crankshaft, engine bearings, flywheels), gear traincomponents (e.g., gearbox, gears, output shaft), and so on.

The knock sensor signals detected may then be compared, for example, byusing a “look up” table to determine certain engine conditions that mayhave cause the knock sensor signals, including changes in valvegeometry. Indeed, rather than applying techniques to separate knock fromother noise data present in knock sensor signals, the techniquesdescribed herein embrace the “spurious” data and apply the data todetermine a variety of engine conditions. By having a look up table ofthe engine's key components related to, for example, crank angle degree,the engine's components can be indexed with respect to temporal windowsrelated to crank angle degree to cross-check and estimate what keycomponent and component condition is likely causing the noise. Forexample, as valve wear, the knock sensor signal may change, and thechange may be used to derive a valve recession measurement. Accordingly,a more proactive engine maintenance and repair process may be provided.

Turning to the drawings, FIG. 1 illustrates a block diagram of anembodiment of a portion of an engine driven power generation system 10.As described in detail below, the system 10 includes an engine 12 (e.g.,a reciprocating internal combustion engine) having one or morecombustion chambers 14 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16,18, 20, or more combustion chambers 14). Though FIG. 1 shows acombustion engine 12, it should be understood that any reciprocatingdevice may be used. An air supply 16 is configured to provide apressurized oxidant 18, such as air, oxygen, oxygen-enriched air,oxygen-reduced air, or any combination thereof, to each combustionchamber 14. The combustion chamber 14 is also configured to receive afuel 20 (e.g., a liquid and/or gaseous fuel) from a fuel supply 22, anda fuel-air mixture ignites and combusts within each combustion chamber14. The hot pressurized combustion gases cause a piston 24 adjacent toeach combustion chamber 14 to move linearly within a cylinder 26 andconvert pressure exerted by the gases into a rotating motion, whichcauses a shaft 28 to rotate. Further, the shaft 28 may be coupled to aload 30, which is powered via rotation of the shaft 28. For example, theload 30 may be any suitable device that may generate power via therotational output of the system 10, such as an electrical generator.Additionally, although the following discussion refers to air as theoxidant 18, any suitable oxidant may be used with the disclosedembodiments. Similarly, the fuel 20 may be any suitable gaseous fuel,such as natural gas, associated petroleum gas, propane, biogas, sewagegas, landfill gas, coal mine gas, for example.

The system 10 disclosed herein may be adapted for use in stationaryapplications (e.g., in industrial power generating engines) or in mobileapplications (e.g., in cars or aircraft). The engine 12 may be atwo-stroke engine, three-stroke engine, four-stroke engine, five-strokeengine, or six-stroke engine. The engine 12 may also include any numberof combustion chambers 14, pistons 24, and associated cylinders 26(e.g., 1-24). For example, in certain embodiments, the system 10 mayinclude a large-scale industrial reciprocating engine 12 having 4, 6, 8,10, 16, 24 or more pistons 24 reciprocating in cylinders 26. In somesuch cases, the cylinders 26 and/or the pistons 24 may have a diameterof between approximately 13.5-34 centimeters (cm). In some embodiments,the cylinders 26 and/or the pistons 24 may have a diameter of betweenapproximately 10-40 cm, 15-25 cm, or about 15 cm. The system 10 maygenerate power ranging from 10 kW to 10 MW. In some embodiments, theengine 12 may operate at less than approximately 1800 revolutions perminute (RPM). In some embodiments, the engine 12 may operate at lessthan approximately 2000 RPM, 1900 RPM, 1700 RPM, 1600 RPM, 1500 RPM,1400 RPM, 1300 RPM, 1200 RPM, 1000 RPM, 900 RPM, or 750 RPM. In someembodiments, the engine 12 may operate between approximately 750-2000RPM, 900-1800 RPM, or 1000-1600 RPM. In some embodiments, the engine 12may operate at approximately 1800 RPM, 1500 RPM, 1200 RPM, 1000 RPM, or900 RPM. Exemplary engines 12 may include General Electric Company'sJenbacher Engines (e.g., Jenbacher Type 2, Type 3, Type 4, Type 6 orJ920 FleXtra) or Waukesha Engines (e.g., Waukesha VGF, VHP, APG, 275GL),for example.

The driven power generation system 10 may include one or more knocksensors 32 suitable for detecting engine “knock” and/or other runcharacteristics of the engine 12. The knock sensor 32 may be any sensorconfigured to sense vibration caused by the engine 12, such as vibrationdue to detonation, pre-ignition, and or pinging. The knock sensor 32 isshown communicatively coupled to a controller (e.g., a reciprocatingdevice controller), engine control unit (ECU) 34. During operations,signals from the knock sensors 32 are communicated to the ECU 34 todetermine if knocking conditions (e.g., pinging), or other behaviorsexist. The ECU 34 may then adjust certain engine 12 parameters toameliorate or avoid the undesirable conditions. For example, the ECU 34may adjust ignition timing and/or adjust boost pressure to avoidknocking. As further described herein, the knock sensors 32 mayadditionally detect other vibrations beyond knocking. It is to be notedthat the same signal may be used for both analysis of knocking as wellas for analysis of other conditions, such as valve recession.

More specifically, the one or more knock sensors 32 may be used todetect a variety of signals and to correlate the signals based on crankangle degrees, noise signatures, or a combination thereof. For example,rather than filtering out “noise” in a signal so that the signal onlydetects knock, the knock sensor's 32 signal used to detect nock may alsobe analyzed in its entirety to determine certain engine conditions,including valve recession. In one embodiment, the signal may be analyzedby using a look table described in more detail below, to determine ifthe noise detected is correlative to a certain crank angle or timing. Ifso, then the condition that caused the noise may be narrowed down to asmall set or a single condition (e.g., a specific valve geometry orvalve geometry range). Additionally or alternatively, a noise signatureanalysis may be performed, and the noise signature of the detectednoise, in combination with the look up table, may narrow down thecondition set even further.

FIG. 2 is a side cross-sectional view of an embodiment of a pistonassembly 36 having a piston 24 disposed within a cylinder 26 (e.g., anengine cylinder) of the reciprocating engine 12. The cylinder 26 has aninner annular wall 38 defining a cylindrical cavity 40 (e.g., bore). Thepiston 24 may be defined by an axial axis or direction 42, a radial axisor direction 44, and a circumferential axis or direction 46. The piston24 includes a top portion 48 (e.g., a top land). The top portion 48generally blocks the fuel 20 and the air 18, or a fuel-air mixture, fromescaping from the combustion chamber 14 during reciprocating motion ofthe piston 24.

As shown, the piston 24 is attached to a crankshaft 50 via a connectingrod 52 and a pin 54. Also shown is a counterweight 55 of the crankshaft50 useful in balancing a weight of a crank throw. The crankshaft 50translates the reciprocating linear motion of the piston 24 into arotating motion. As the piston 24 moves, the crankshaft 50 rotates topower the load 30 (shown in FIG. 1), as discussed above. As shown, thecombustion chamber 14 is positioned adjacent to the top land 48 of thepiston 24. A fuel injector 56 provides the fuel 20 to the combustionchamber 14, and an intake valve 58 controls the delivery of air 18 tothe combustion chamber 14. An exhaust valve 60 controls discharge ofexhaust from the engine 12. However, it should be understood that anysuitable elements and/or techniques for providing fuel 20 and air 18 tothe combustion chamber 14 and/or for discharging exhaust may beutilized, and in some embodiments, no fuel injection is used. Inoperation, combustion of the fuel 20 with the air 18 in the combustionchamber 14 cause the piston 24 to move in a reciprocating manner (e.g.,back and forth) in the axial direction 42 within the cavity 40 of thecylinder 26.

During operations, when the piston 24 is at the highest point in thecylinder 26 it is in a position called top dead center (TDC). When thepiston 24 is at its lowest point in the cylinder 26, it is in a positioncalled bottom dead center (BDC). As the piston 24 moves from top tobottom or from bottom to top, the crankshaft 50 rotates one half of arevolution. Each movement of the piston 24 from top to bottom or frombottom to top is called a stroke, and engine 12 embodiments may includetwo-stroke engines, three-stroke engines, four-stroke engines,five-stroke engine, six-stroke engines, or more.

During engine 12 operations, a sequence including an intake process, acompression process, a power process, and an exhaust process typicallyoccurs. The intake process enables a combustible mixture, such as fueland air, to be pulled into the cylinder 26, thus the intake valve 58 isopen and the exhaust valve 60 is closed. The compression processcompresses the combustible mixture into a smaller space, so both theintake valve 58 and the exhaust valve 60 are closed. The power processignites the compressed fuel-air mixture, which may include a sparkignition through a spark plug system, and/or a compression ignitionthrough compression heat. The resulting pressure from combustion thenforces the piston 24 to BDC. The exhaust process typically returns thepiston 24 to TDC while keeping the exhaust valve 60 open. The exhaustprocess thus expels the spent fuel-air mixture through the exhaust valve60. It is to be noted that more than one intake valve 58 and exhaustvalve 60 may be used per cylinder 26.

The engine 12 may also include a crankshaft sensor 62, one or more knocksensors 32, and the engine control unit (ECU) 34, which includes aprocessor 64 and memory 66 (e.g., non-transitory computer readablemedium). The crankshaft sensor 62 senses the position and/or rotationalspeed of the crankshaft 50. Accordingly, a crank angle or crank timinginformation may be derived. That is, when monitoring combustion engines,timing is frequently expressed in terms of crankshaft 50 angle. Forexample, a full cycle of a four stroke engine 12 may be measured as a720° cycle. The one or more knock sensors 32 may be a Piezo-electricaccelerometer, a microelectromechanical system (MEMS) sensor, a Halleffect sensor, a magnetostrictive sensor, and/or any other sensordesigned to sense vibration, acceleration, sound, and/or movement. Inother embodiments, sensor 32 may not be a knock sensor in thetraditional sense, but any sensor that may sense vibration, pressure,acceleration, deflection, or movement.

Because of the percussive nature of the engine 12, the knock sensor 32may be capable of detecting engine vibrations and/or certain“signatures” related to a variety of engine conditions even when mountedon the exterior of the cylinder 26. The one or more knock sensors 32 maybe disposed at many different locations on the engine 12. For example,in FIG. 2, one knock sensors 32 is shown on the head of the cylinder 26.In other embodiments, one or more knock sensors 32 may be used on theside of the cylinder 26. Additionally, in some embodiments, a singleknock sensor 32 may be shared, for example, with one or more adjacentcylinders 26. In other embodiments, each cylinder 26 may include one ormore knock sensors 32 on either or both sides of a cylinder 26. Thecrankshaft sensor 62 and the knock sensor 32 are shown in electroniccommunication with the engine control unit (ECU) 34. The ECU 34 includesa processor 64 and a memory 66. The memory 66 may store non-transitorycode or computer instructions that may be executed by the processor 64.The ECU 34 monitors and controls and operation of the engine 12, forexample, by adjusting spark timing, valve 58, 60 timing, adjusting thedelivery of fuel and oxidant (e.g., air), and so on.

Knock sensors 32 are used to detect engine knock. Engine knock is thepremature combustion of fuel outside the envelope of normal combustion.In some cases, the ECU 34 may attempt to reduce or avoid engine knockwhen it occurs by adjusting the operating parameters of the engine. Forexample, the ECU 34 may adjust the air/fuel mix, ignition timing, boostpressure, etc. in an effort to reduce or avoid engine knock. However,knock sensors may also be used to detect other vibrations in an engineunrelated to engine knock. More specifically, the same knock sensorsignal may be processed both to detect knock as well as to detect otherconditions, including valve recession conditions. In valve recession,the valve 60 or a valve seat (e.g., valve seat ring) 67 may experiencewear and valve clearance or “lash” may be reduced, causing unwantedescape of combustion gases which may cause further wear to the valve 60and/or to valve seat 67. Valve recession or valve wear may be derived asdescribed below.

FIG. 3 is an embodiment of a raw engine noise plot 68 derived (e.g., bythe ECU 34) of noise data measured by a single knock sensor 32 mountedon a single cylinder 26 in which x-axis 70 is time and the y-axis 72 israw noise amplitude. In the depicted embodiment, an amplitude curve 74of the knock sensor 32 signal is shown. That is, the raw signal 74includes amplitude measurements of vibration data (e.g., noise, sounddata) sensed via the knock sensor 32 and plotted against time. It shouldbe understood that this is merely a plot 68 of a sample data set, andnot intended to limit plots generated by the ECU 34. It should also beunderstood that plot 68 is of a signature from one knock sensor 32mounted to one cylinder 26. In other embodiments there may be multiplesignatures from multiple knock sensors mounted to multiple cylinders,e.g., mating cylinders. The raw signal 74 may then be further processed,as described in more detail below, including via the use of a look uptable and/or signature analysis.

With respect to signature analysis, as shown in FIG. 4, signals can befiltered into a combustion signature 76 and a valve signature 78. Eventscan then be derived from the signatures and the timing of those eventschecked via look up table(s). Once data from the one or more knocksensors 32 is collected, one or more filters may be applied to the datato derive a combustion signature 76 (i.e., noise attributable tocombustion events) and a valve signature 78 (i.e., noise attributable tovalve 58, 60 movement). The combustion signature 76 and valve signature78 may be derived by applying filters, fast Fourier transforms (FFT), orapplying other digital signal processing (DSP) techniques to the sampleddata. For example, the ECU 34 may derive the combustion signature 76 byapplying a low pass filter at 1200 Hz or a band pass filter from 0.5 Hzto 1200 Hz. The valve signature may be derived using a band pass filterfrom 12 kHz to 18 kHz. FIG. 4 is an embodiment of a sample plot 82 of acombustion signature 76 and a valve signature 78 over a first completeintake, compression, and combustion and exhaust cycle. The x-axis 84 isshown as time in seconds, but may also be shown as crank angle. They-axis 86 on the left corresponds to the valve signature 78, and they-axis 88 on the right corresponds to the combustion signature 76. Eachof the y-axes 86, 88 represents the amplitude of the corresponding noisesignature 76, 78. Depending upon the measurement technique and thepreference of the user, the units may be dB, volts, or some other unit).Note that the scales of the y-axes 86, 88 may be different because theamplitudes of the two signatures 76, 78 are likely to be different. FIG.4 is illustrative of data that may be undergoing data processing, forexample, via a process described in more detail with respect to thefigures below. The data for FIG. 4 may include data transmitted via theknock sensor 32 and the crank angle sensor 62 once the ECU 34 hasderived a combustion signature 76 and a valve signature 78 from the datausing digital signal processing (DSP) techniques. Furthermore, for thesake of clarity, only a single combustion signature and a single valvesignature are shown in FIG. 4. It should be understood, however, thatthe same or similar processing may be performed on more than one knocksensor 32 mounted to more than one cylinder.

The combustion signature 76 includes significant combustion events, suchas peak firing pressure (PFP) of both the measured cylinder 26, and amating cylinder 80 (i.e., the cylinder in the engine that is 360 degreesout of phase with the measured cylinder 26). The valve signature 78includes the closing of the intake valve 58 and exhaust valve 60. Somecombustion events, such as PFP (of both the measured cylinder 26 and themating cylinder 80), may appear in both the combustion signature 76 andthe valve signature 78. FIG. 4 shows slightly more than one completecombustion cycle, or 720 degrees of rotation (two complete revolutions)at the crankshaft 50. Each cycle includes intake, compression,combustion, and exhaust.

In one example, the signatures 76, 78, and/or the raw signal 74 may beprocessed to determine if any abnormal conditions exist. In oneembodiment, the signatures 76, 78, and/or the raw signal 74 may becompared to a baseline, and the comparison used to determine thatsufficient differences exist such that a condition affecting engineperformance is occurring. In certain embodiments, the baseline may besignals representative of the engine 12 operating with valve 60 and/orvalve seat 67 with no wear (e.g., new valves and valve seats). Then, aswear occurs, deviations from the baseline may be detected and used todetermine valve 60 and/or valve seat 67 wear, such as recessionmeasurements. For example, as wear occurs, a valve 60 closing angle maychange. For example, the crank angle of the crank 50 may shift slightly,resulting in a new valve closing angle. The valve 60 closing angle maybe representative of a recession or lash measure. That is, deviationsfrom a baseline valve closing angle may be converted into a recessionmeasurement in, for example, millimeters. In one example, a table may beused, where deviations, e.g., in degrees, may be converted to recessionin millimeters, inches, etc. In other examples, equation(s) (e.g.,geometric equations) may be used to convert from closing angles torecession measurements.

Indeed, the comparison between the signatures 76, 78, and/or the rawsignal 74 and the baseline may include a crank angle degree or timingcomparison. That, is differences between the signatures 76, 78, and/orthe raw signal 74 and the baseline may be ascertained by comparisonbased on when in the engine combustion cycle the signatures 76, 78,and/or the raw signal 74 was captured, which may be correlative with theposition or crank angle of the crank 50. The baseline may be derived byobserving normal operations of the engine 12 over the course of multiplecombustion cycles.

In another embodiment, the determination that an abnormal condition ofsome sort exists may be made by other techniques, such as lubricantanalysis, emissions analysis, wear debris detection, and the like.Regardless of the techniques used to determine that some sort ofabnormality is occurring, including baselining the signatures 76, 78,and/or the raw signal 74, the techniques described herein mayadditionally or alternatively aid in determining what component orcomponents may be involved. More specifically, the techniques describedherein may apply a look up table to determine component(s) of the engine12 involved in the current condition, such as the valve 60 and/or thevalve seat 67 wear.

In one embodiment, the look up table for a twelve-cylinder embodiment ofthe engine 12 may include a first Knock sensor window “open”, followedby one or more position columns. The position columns may include camposition (degrees), crank position (degrees), #1 Right Cylinder PistonPosition (inches from TDC), #1 Right Cylinder Counterweight PositionAngle from Highest Point where Highest point=0 degrees, #6 Left CylinderPiston Position (inches from TDC), #6 Left Cylinder CounterweightPosition Angle from Highest Point where Highest point=0 degrees, #5Right Cylinder Piston Position (inches from TDC), #5 Right CylinderCounterweight Position Angle from Highest Point where Highest point=0degrees, #2 Left Cylinder Piston Position (inches from TDC), #2 LeftCylinder Counterweight Position Angle from Highest Point where Highestpoint=0 degrees, #3 Right Cylinder Piston Position (inches from TDC), #3Right Cylinder Counterweight Position Angle from Highest Point whereHighest point=0 degrees, #4 Left Cylinder Piston Position (inches fromTDC), and #4 Left Cylinder Counterweight Position Angle from HighestPoint where Highest point=0 degrees.

The Knock sensor window “open” column may refer to a time window (e.g.,time range) or crank angle window (e.g., angle range) at which aparticular sensor 32 is more suited to derive engine 12 conditions,based on the one or more position columns. For example, the knock sensor32 disposed in the #1 right cylinder 26 may be more suitable at a windowor range when the camshaft position (e.g., crank position (degrees)column) is between 0 and 15 degrees. Likewise, the remainder columnscrank position (degrees), #1 Right Cylinder Piston Position (inches fromTDC), #1 Right Cylinder Counterweight Position Angle from Highest Pointwhere Highest point=0 degrees, #6 Left Cylinder Piston Position (inchesfrom TDC), #6 Left Cylinder Counterweight Position Angle from HighestPoint where Highest point=0 degrees, #5 Right Cylinder Piston Position(inches from TDC), #5 Right Cylinder Counterweight Position Angle fromHighest Point where Highest point=0 degrees, #2 Left Cylinder PistonPosition (inches from TDC), #2 Left Cylinder Counterweight PositionAngle from Highest Point where Highest point=0 degrees, #3 RightCylinder Piston Position (inches from TDC), #3 Right CylinderCounterweight Position Angle from Highest Point where Highest point=0degrees, #4 Left Cylinder Piston Position (inches from TDC), and #4 LeftCylinder Counterweight Position Angle from Highest Point where Highestpoint=0 degrees may include data related to when a particular knocksensor 32 (e.g., #1 right, #1 left, #2 right, #2 left, #3 right, #3left, #4 right, #4 left, #5 right, #5 left, #6 right, #6 left) is moreeffective at certain positions.

The look up table may be created, for example, to correlate noisereceived via the knock sensors 32 and corresponding position columns,with one or more engine 12 conditions, such as conditions affectingcylinder 26 head components (e.g., cylinder head and gaskets), cylinder26 block components (e.g., cylinder block, cylinder sleeves), valve 58,60 train components (e.g., valves, valve seats, valve stems), camshaft50 and drive components (e.g., camshaft, cam lobes, timing belts/chains,tensioners), piston 24 components (e.g., pistons, piston rings,connection rods), crankshaft 50 assembly components (e.g., crankshaft,engine bearings, flywheels), gear train components (e.g., gearbox,gears, output shaft), and so on. In one embodiment, the crankshaftsensor 62 may aid in the correlation, for example, by additionallyproviding for crankshaft 50 position data (e.g., crank position(degrees) column). By correlating which of a particular knock sensor 32(e.g., #1 right, #1 left, #2 right, #2 left, #3 right, #3 left, #4right, #4 left, #5 right, #5 left, #6 right, and/or #6 left knock sensor32, where the number and position corresponds to a cylinder 32 numberand position of, for example, the 12 cylinder embodiment of the engine12), and when the knock sensor 32 detected the unusual or unexpectednoise, the techniques described herein may provide for an estimate ofwhich component is likely causing the unexpected noise.

In certain embodiments, the estimate is an estimated recession measure.For example, various rows in the look up table would contain deviationsfrom a baseline (e.g., baseline with new valve 60, seat 67)representative of various valve closing angles. In one embodiment, morethan one look up table may be used, each table correlating noise to aspecific component, set of components, engine condition, set of engineconditions, or a combination thereof. In another embodiment, the set ofengine 12 conditions correlative to the position columns and the Knocksensor window “open” column may be stored as additional Conditioncolumns in the lookup table(s). Accordingly, the techniques describedherein may enable a real time detection of engine 12 conditions through,for example, existing knock sensors 32, which may result in proactiveengine maintenance and repair processes.

FIG. 5 is a flow chart depicting a process 150 suitable for analyzingvibration data via the knock sensors 32 and lookup table(s). The process150 may be implemented as computer code or instructions executable viathe processor 64 and stored in the memory 66. In the depictedembodiment, the process 150 may create (block 152) one or more lookuptables 154. As mentioned above, the look up table(s) 154 may be createdto correlate noise received via the knock sensors 32 and correspondingposition columns, with one or more engine 12 conditions, such asconditions affecting cylinder 26 head components (e.g., cylinder headand gaskets), cylinder 26 block components (e.g., cylinder block,cylinder sleeves), valve 58, 60 train components (e.g., valves, valveseats, valve stems), camshaft 50 and drive components (e.g., camshaft,cam lobes, timing belts/chains, tensioners), piston 24 components (e.g.,pistons, piston rings, connection rods), crankshaft 50 assemblycomponents (e.g., crankshaft, engine bearings, flywheels), gear traincomponents (e.g., gearbox, gears, output shaft), and so on.

In one embodiment of a twelve-cylinder engine 12, the lookup table(s)154 may include a Knock sensor window “open” column followed by one ormore position columns. The position columns may include: cam position(degrees), crank position (degrees), #1 Right Cylinder Piston Position(inches from TDC), #1 Right Cylinder Counterweight Position Angle fromHighest Point where Highest point=0 degrees, #6 Left Cylinder PistonPosition (inches from TDC), #6 Left Cylinder Counterweight PositionAngle from Highest Point where Highest point=0 degrees, #5 RightCylinder Piston Position (inches from TDC), #5 Right CylinderCounterweight Position Angle from Highest Point where Highest point=0degrees, #2 Left Cylinder Piston Position (inches from TDC), #2 LeftCylinder Counterweight Position Angle from Highest Point where Highestpoint=0 degrees, #3 Right Cylinder Piston Position (inches from TDC), #3Right Cylinder Counterweight Position Angle from Highest Point whereHighest point=0 degrees, #4 Left Cylinder Piston Position (inches fromTDC), and #4 Left Cylinder Counterweight Position Angle from HighestPoint where Highest point=0.

Each row of the lookup table(s) 154 may include a specific knock sensor32 (e.g., #1 right, #1 left, #2 right, #2 left, #3 right, #3 left, #4right, #4 left, #5 right, #5 left, #6 right, and/or #6 left sensor 32)in the Knock sensor window “open” column and corresponding positionvalues for the position columns. In one embodiment, a test bed engine 12may be instrumented and used to create the lookup table(s) 154. Forexample, noise related to the one or more engine 12 conditions listedabove may be captured and analyzed, and the columns of the lookuptable(s) 154 associated with the noise. In use, the knock sensor(s) 32may sense (block 156) engine noise during engine 12 operations. Certainnoises, such as unusual noises, may be found, for example, by using thebaselining and/or signature techniques described above, or by othertechniques. The noises may then be correlated by applying (block 158)the lookup table(s) 154. For example, the relevant knock sensor(s) 32that detect the noise and/or the signals from the crankshaft sensor 62may be used to derive values for the position columns of the table(s)154. Based on the noise detected and/or the position of certaincomponents (e.g., derived by using the position columns of the lookuptable(s) 154), certain engine conditions may be derived (block 160). Asmentioned earlier, a derived condition may be a variation from abaseline closing angle. That is, if the baseline closing angle is anumber, like 386 degrees, then knock sensor 32 signals may be received,correlated to an engine condition (e.g., correlated to be a signalrepresentative of deviation from valve closing baseline), and the looktable(s) 154 may then be used to determine the deviation. For example,recognition software may be trained to recognize the knock sensor signalas being a valve closing event signal deviating from a baseline (e.g.,valve closing baseline) based on crank angle and then the recognitionsoftware may “point” to a row corresponding to the deviation in the lookup table(s) 154, which may include the degrees of deviation in valveclosing and/or a valve recession measurement.

For example, based on cam position (degrees), crank position (degrees),#1 Right Cylinder Piston Position (inches from TDC), #1 Right CylinderCounterweight Position Angle from Highest Point where Highest point=0degrees, #6 Left Cylinder Piston Position (inches from TDC), #6 LeftCylinder Counterweight Position Angle from Highest Point where Highestpoint=0 degrees, #5 Right Cylinder Piston Position (inches from TDC), #5Right Cylinder Counterweight Position Angle from Highest Point whereHighest point=0 degrees, #2 Left Cylinder Piston Position (inches fromTDC), #2 Left Cylinder Counterweight Position Angle from Highest Pointwhere Highest point=0 degrees, #3 Right Cylinder Piston Position (inchesfrom TDC), #3 Right Cylinder Counterweight Position Angle from HighestPoint where Highest point=0 degrees, #4 Left Cylinder Piston Position(inches from TDC), and/or #4 Left Cylinder Counterweight Position Anglefrom Highest Point where Highest point=0, it may be possible to moreeasily narrow down (or fully derive) (block 160) that the noise capturedby the knock sensor(s) 32 is due to a certain engine condition (e.g.,valve closing event or deviation from a baseline valve closing angle),or subset of engine conditions.

The process 150 may then communicate (block 162) the derived engine 12conditions. For example, the process 150 may display the one or moreengine 12 conditions (e.g., valve recession measurement) in a displaycommunicatively coupled to the ECU 34, set an error code (e.g.,controller area network [CAN] code, on-board diagnostics II [OBD-II]code), set an alarm or an alert, and so on. By correlating noise vialookup table(s) 154, the techniques described herein may enhance engineoperations and maintenance processes.

FIG. 6 is a graph 200 illustrating an embodiment of various valve 60closing angles shown in axis 202 graphed at various operating enginehours shown in an axis 204. In the depicted embodiment, at zerooperating hours, a baseline 206 having 386 degrees of valve 60 closingangle is depicted. The baseline 206 may be representative of anadjustment (e.g., valve lash adjustment) and/or installation of newvalve seats and/or new valves. As the engine 12 operates, wear causeclosing angle changes until at time T1 the closing angle may now be at374 degrees. The systems and methods described herein may have a rangeof valve closing angles and corresponding recession values at which avalve lash adjustment may be recommended. Likewise a new valve ringand/or a new valve may be recommended. Accordingly, the graph shows apoint 208 after valve adjustment and/or new valve seat installationand/or new valve installation.

Subsequent points in the graph show changes in valve closing anglesafter more operating hours. That is, operating hours after T1 showchanges in valve closing angles which again may be due to wear. Atcertain points, such as point 210, alarms/alerts, and so on, may beprovided to the engine 12 operator, to ask the operator to once againperform a valve lash adjustment (or install new valve seats and/or newvalves). It is to be understood that the degree values show in axis 202are for example only, and other values may be used depending on the typeof engine 12 being used. The graph 200 may also be provided to engine 12operators via a vehicle display, a log, printed media, and so on.

The graph 200 may be dynamically derived via the techniques describedherein. That is, a running tally may be kept of operating hours for theengine 12, and after the passage of a certain time (e.g., minute, 5minutes, 15 minutes, 30 minutes, 1 hour) the ECU 34 may then derive avalve closing angle, for example via block 160 above. According, a valveclosing angle may be correlated to a given operating time for the engine12. As mentioned earlier, valve closing angles may be converted intoother measures such as valve lift. Turning now to FIG. 7, the figure isa graph 300 showing an embodiment of various crank degrees (e.g., valveclosing degrees) in axis 302 being converted into valve lift points inaxis 304, where valve lift is representative of valve recessionmeasurement. In the depicted example, given an certain crank angle(e.g., 374 degrees), the graph 300 may then provide a correspondingvalve lift measure (e.g., 0.237 mm). It is to be understood that thevalues in axis 302 and 304 are for example only.

By first deriving valve closing angles and then providing forcorresponding valve lift measurements, the techniques described hereinmay enable improved engine 12 maintenance and increase life. Forexample, a range of valve lift may be set, and if a derived valve liftvalue is outside the range then the engine 12 operator may be notified.The engine 12 may then be maintained in a condition-based maintenance(CBM) mode, as opposed to on a schedule mode. The schedule mode mayresult in, for example, valve adjustments that performed unnecessarilytoo many times or not as often as the actual valve recession would callfor.

Technical effects of the invention include detecting engine vibrationsvia certain sensors, such as knock sensors. Certain lookup table(s) maybe created, suitable for associating one or more knock sensor “windows”with one or more conditions of certain engine components. The vibrationsare correlated, via the one or more lookup tables and/or crankshaftsensor data, and certain engine conditions may be detected. The engineconditions include valve wear, valve seat wear, and the like, which maybe converted into certain measurements, such as valve recessionmeasurements.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal language of the claims.

1. A method, comprising: receiving a signal representative of an enginevibration transmitted via a knock sensor, wherein the knock sensor isdisposed in an engine; deriving a valve wear measurement duringoperation of the engine based on the signal; and communicating the valvewear measurement.
 2. The method of claim 1, wherein deriving the valvewear measurement comprises deriving an exhaust valve lift measurement.3. The method of claim 2, wherein deriving the exhaust valve liftmeasurement comprises deriving an exhaust valve closing angle based onthe signal and then converting the exhaust valve closing angle into theexhaust valve lift measurement.
 4. The method of claim 1, whereinderiving the valve wear measurement comprises using at least one row ofa lookup table based on the signal.
 5. The method of claim 1, whereinderiving a valve wear measurement during operation of the engine basedon the signal comprises applying a signal baseline to the signal.
 6. Themethod of claim 5, wherein the signal baseline comprises a valveadjustment baseline, a new valve installation baseline, a new valve seatinstallation baseline, or a combination thereof.
 7. The method of claim1, wherein deriving a valve wear measurement during operation of theengine based on the signal comprises applying a crank angle measurement.8. The method of claim 1, wherein deriving the valve wear measurementcomprises capturing a second signal via a second knock sensor, whereinthe second signal is representative of an intake valve closing andwherein the first signal is representative of an exhaust valve closing.9. The method of claim 1, comprising adjusting a valve lash based whenthe valve wear measurement exceeds a range.
 10. A system, comprising: anengine control system comprising a processor configured to: receive asignal representative of an engine vibration transmitted via a knocksensor, wherein the knock sensor is disposed in an engine; derive avalve wear measurement during operation of the engine based on thesignal; and communicate the valve wear measurement.
 11. The system ofclaim 10, wherein the processor is configured to derive the valve wearmeasurement by deriving an exhaust valve lift measurement.
 12. Thesystem of claim 11, wherein deriving the exhaust valve lift measurementcomprises deriving an exhaust valve closing angle based on the signaland then converting the exhaust valve closing angle into the exhaustvalve lift measurement.
 13. The system of claim 11, wherein theprocessor is configured to derive the valve wear measurement by using atleast one row of a lookup table based on the signal.
 14. The system ofclaim 11, wherein the processor is configured to derive the valve wearmeasurement by applying a signal baseline to the signal.
 15. A tangible,non-transitory computer readable medium storing code configured to causea processor to: receive a signal representative of an engine vibrationtransmitted via a knock sensor, wherein the knock sensor is disposed inan engine; derive a valve wear measurement during operation of theengine based on the signal; and communicate the valve wear measurement.16. The tangible, non-transitory computer readable medium of claim 15,wherein causing the processor to derive the valve wear measurementcomprises causing the processor to derive an exhaust valve liftmeasurement.
 17. The tangible, non-transitory computer readable mediumof claim 16, wherein causing the processor to derive the exhaust valvelift measurement comprises causing the processor to derive an exhaustvalve closing angle based on the signal and then to convert the exhaustvalve closing angle into the exhaust valve lift measurement.
 18. Thetangible, non-transitory computer readable medium of claim 15, whereinthe code is configured to cause the processor to derive the valve wearmeasurement by using at least one row of a lookup table based on thesignal.
 19. The tangible, non-transitory computer readable medium ofclaim 15, wherein the code is configured to cause the processor toderive the valve wear measurement by applying a signal baseline to thesignal.
 20. The tangible, non-transitory computer readable medium ofclaim 19, wherein the baseline comprises a valve closing angle.